Every day, I hear about people whose PCs crash or hang without apparent reason. As many of you use PCs to DJ, I thought it's about time you found out about ESD damage.
I work on Enterprise computers where applications are mission critical (ie: banking, telecomms, etc...) and our procedures when working on this kit are extemely stringent as our customers cannot afford unexpected downtime. We spend a lot of time learning about this and how to avoid it. A little bit like a PC DJ in the middle of a set then.
However, all is not well in the PC industry. I still see and hear about so called *experts* working in shops, repair centres etc., not using basic ESD precautions when handling electronic components such as hard disks, memory, CPUs, pci cards, motherboards, etc.. These guys are compromising the reliability of your kit.
All these devices when manufactured, are shipped in anti static packaging. They must be opened by someone at an anti static workstation who is wearing an earth strap. The equipment the component is inserted into should be connected to this, the idea being that no static charges can affect the component. You can get portable workstations and disposable mats to allow you to work on equipment in the field.
What happens when a component is affected by an ESD event depends on many factors such as how damp the air is, how high the static charge you are carrying is etc... When an ESD event damages a chip, the damage may not be apparent for some time and may be intermittent in nature. Let's imagine an ESD event hits a circuit causing a hole in a track or a wire. Current may still flow through it (you will think that the component works), but over time the area surrounding the hole will completely fuse as it has been carrying far more current than it can cope with. This will then show as a failure. This can take seconds, weeks, months, years...
My last example is when I walked into my local PC shop looking for a DIMM (memory chip) for a friend. The guy picked up a DIMM from the counter and handed it to me. I refused, and waked out.
I can already hear some of you thinking "crap, I've never had a problem with ESD and I don't use a strap". Think again, how can you be sure? You cannot see ESD damage, computer manufacturers think it counts for about 80% of component failure in the field.
So, when you are building a system for DJing, find out how to do it properly. Personally, I would NOT get a system custom built by a friend or shop, I would buy something manufactured in a factory like an Apple or Dell (for example) system where you can be completely confident that no one has opened the thing up without ESD precautions to fit a sound card or whatever.
Here is an article to describe a bit more about ESD:
Full Version: ESD - Electro Static Discharge
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About ESD (ElectroStatic Discharge) ESD, or ElectroStatic Discharge, is the term most often used to describe the sensitivity of modern electronic components to static electrical charges. Many of these components, including computer chips, electronic assemblies and circuit boards, can be damaged beyond repair by an electrical discharge as low as 20 volts. Manufacturers of electronic components and assemblers of electronic systems must control static discharges in their processes through the use of an effective ESD program. If they fail to take the necessary measures to control static electricity many of the components or systems they produce will fail to work or will suffer a reduced operating life -- costing the company tens of thousands of dollars in product losses and defects. What Is Static? Everyone has experienced static discharge at one time or another. A simple example would be when you walk across a carpeted floor and reach for the door handle. That snapping noise accompanied by an uncomfortable sting in the tips of your fingers is the discharge of static electricity. Your body actually built up an electrical potential of several thousand volts which discharged through the air when your fingers got close to the door handle. Because the electrical potential was on the order of 35,000 volts you actually produced an arc of electric current that overcame the normally insulative qualities of air. And, just so you know, the supreme ESD is a lightning strike. ESD And Electronics ESD is an insidious electronics killer. As you read above, ESD occurs when the electrical potential of one object is different than the electrical potential of another. ESD damage can occur in electronic components with as little as 20 volts. Although this minute discharge cannot be felt, the effect on electronic devices can be devastating. Common, everyday objects used in the workplace such as Styrofoam coffee cups, flooring materials, storage bins, desktops, and even ordinary clothing are all sources of static generating materials. Without an effective ESD program in place, workers who handle electronic parts will trash them without any outside indication. Workers in the electronics industry must circumvent any potential ESD damage by creating ESD-controlled work environments and practicing ESD awareness. |
By the way, this also applies to other electronic kit like your CD players, mixer, amps etc...
I think that half the time I am regarded as weird enough for bringing up topics that trouble me and seem like big issues, but I am delighted that someone ELSE brought this up!
Frequently, when enquiring about a repair the local disco shop will say "Oh we've been waiting for a part, but look it came in this morning...." proudly brandishing the part with bare fingers. On several occasions I have said politely "shouldn't you be handling that with some kind of protection?" This has been met with ridicule or a head-patting explanation of they knew best and not to worry.
I have to confess I have always been dubious about this, because of what I read in computer books, but a part of me (the fair part, that should learn to trust the intuitive part!) also wondered if the issue was more acute in computers cos of the scale of the integration on the chips.
Now having said that, anyone who has ever popped the lid on a Denon or Pioneer deck will know that the chips in them are very large, compared to the AA/Kam/Gemini/Numark/Citronic type of deck.
The large scale integration on the chips are what I presume give those decks some of their unique features in terms of DSP and pitch resolution.
Now, as they say in the Westminster:
A supplementary question for the Right Honorable Member For Horsham North:
"Given the mission critical dimension of DJ gear, to use a term borrowed from our computer friends, would it not be appropriate given the cost of some of these devices, that they come with built-in environmental protection such as dust/humidity seals?"
Or am I being over-paranoid? Seems that any mission-critical PC, even many Media Centre ones come with dust filters and suchlike....Surely we need the same level of protection as a device being used to watch Corrie in a living room???
Can items be cleaned/discharged if they have been effected?
I've opened my pc case a few times to insert memory, network cards etc and hadn't taken any of the above precautions, which I guess now means that these components will now be effected, is there anything that I can do to reduce the risk of future failure?
I've opened my pc case a few times to insert memory, network cards etc and hadn't taken any of the above precautions, which I guess now means that these components will now be effected, is there anything that I can do to reduce the risk of future failure?
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| I guess now means that these components will now be effected, |
not necessarily
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| is there anything that I can do to reduce the risk of future failure? |
make sure you are earthed before you handle any ESD sensitive gear
You don't necessarily need an antistatic workstation or any fancy kit though.
I custom build systems and i use the earthed casing as my earth by simply ensuring that i have the power supply connected to the electrical supply but switched off. That way it's only a case of touching the chassis to earth myself and this happens mostly by accident all the time you're working anyway.
One thing to ensure first if working like this is to ensure that there is no other piece of equipment with an earth fault putting a current down the earth elsewhere. Not likely to get to you but better to be safe.
I custom build systems and i use the earthed casing as my earth by simply ensuring that i have the power supply connected to the electrical supply but switched off. That way it's only a case of touching the chassis to earth myself and this happens mostly by accident all the time you're working anyway.
One thing to ensure first if working like this is to ensure that there is no other piece of equipment with an earth fault putting a current down the earth elsewhere. Not likely to get to you but better to be safe.
WRONG 
It is not just a case of earthing the kit and touching the chassis before you work. You do need to be strapped to earth (via a resistor), and the kit needs to be also strapped to earth BEFORE you take any bit of kit apart. The reason is quite simple, as you move around, you make static electricity. When you are charged up, and approach a component/system you will discharge not on contact, but gradually as you get nearer to said component.
Eskie, the damage is non-reversable. You may have been lucky and not damaged anything, but you will never be sure as you cannot test for ESD damage without destroying the item.
I will try and find a pic of a portable ESD kit to attach to this thread later this week...
It is not just a case of earthing the kit and touching the chassis before you work. You do need to be strapped to earth (via a resistor), and the kit needs to be also strapped to earth BEFORE you take any bit of kit apart. The reason is quite simple, as you move around, you make static electricity. When you are charged up, and approach a component/system you will discharge not on contact, but gradually as you get nearer to said component.
Eskie, the damage is non-reversable. You may have been lucky and not damaged anything, but you will never be sure as you cannot test for ESD damage without destroying the item.
I will try and find a pic of a portable ESD kit to attach to this thread later this week...
I just use a anti static wrist thingy... and statise myself before..
Haven't run into any problems yet.
Haven't run into any problems yet.
Just super glue your hand to the kitchen sink problem solved! 
Why not go for a bog wash? It'll get rid of them pesky electrons! 
I'm sorry, i didn't make myself clear. I meant that by having the power cord connected you have a suitable place to discharge yourself prior to handling components. I was not suggesting that you should just dive in and rely on the fact you will touch the casing at some point.
In 10 years of working like this i'm yet to kill a component.
In 10 years of working like this i'm yet to kill a component.
| QUOTE (norty303 @ Sep 26 2005, 11:13 PM) |
| I'm sorry, i didn't make myself clear. I meant that by having the power cord connected you have a suitable place to discharge yourself prior to handling components. I was not suggesting that you should just dive in and rely on the fact you will touch the casing at some point. In 10 years of working like this i'm yet to kill a component. |
I understand what you are saying, and it is of course true to a good degree, but I was suggesting that even once you have touched the case and discharged yourself, as soon as you let go you build up charge again by moving around. It only takes 20 Volts to create an ESD event. Just moving your hand to pick up a screwdriver can create this.
On a course we did, we actually measured about 300 volts of static electricity between touching the case and moving my arm to pick up someting on the table. I was gobsmacked.
Now then, you remember that polyester tanktop you always wear?
So do you just recommend using a anti static wrist strap attached to the case with power on? For handling components?
Don't forget that static damage to a component may not show up at once but can take months or even years to cause a fault.
So it is impossible to say that you have not damaged a component in 10 years. I am sure that not everything you have built is still running.
Some of the failures you just assume is normal will probably have been caused by static damage when the unit was built.
As a design engineer I am paid to know this stuff.
Dicky
So it is impossible to say that you have not damaged a component in 10 years. I am sure that not everything you have built is still running.
Some of the failures you just assume is normal will probably have been caused by static damage when the unit was built.
As a design engineer I am paid to know this stuff.
Dicky
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| So it is impossible to say that you have not damaged a component in 10 years. I am sure that not everything you have built is still running. Some of the failures you just assume is normal will probably have been caused by static damage when the unit was built. |
That's a fairly sure thing with PC components though. Naturally PSU's and Hard disks fail due to mechanical breakdown. It happens in commercially built units all the time. I've yet to know of a mobo, memory or processor failure in any of my units where they haven't been junked for some other (obsolete) reason.
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| The reason is quite simple, as you move around, you make static electricity. When you are charged up, and approach a component/system you will discharge not on contact, but gradually as you get nearer to said component |
This however is not strictly true.
Static electricity is only produced by man made fibres - nylon, lycra etc. and treated wool for example. Rubber shoes on a nylon carpet as well!
By touching the metal of a computer case, will only change you level of Static electricty to that of the computer - which is why the pc should be grounded- plugged in. If the pc is not plugged in, and you are grounded then, when you touch the pc you can actually get a shock from the machine if there is sufficent static in the device.
Not everyone is equiped with a full ESD work station, and i do actually carry a mobile version of it. Bu there are som situations when an esd mat cannot be used and so other means of grounding both yourself, and the equipment need to be found.
I will admit, that when i am working on my own machines, i do not use any esd devices othere than a mains cord. As long as you know how to discharge yourself and the components you are useing then there will never be a problem.
The easiest way is to touch the pc case, but as soon as you let go there is a possibility to re charge as you move, so the best way is to keep in contact with the chassis at all times - lean on it! And as for touching the components DONT. Expansion cards have there own ground - the metal bracket use that. Hard drives have a metal frame, touch that. Floppy drives and CD roms come in Anti static bages, but ARE NOT sensitive devices...
So as long as you dont touch any part of the circuit board on any device, you can quite safetly move any component around....
.... But what about the Power supply????
Well, Leave it plugged in to the wall, remove all the intenal plugs, then unbolt the psu from the case. only when the psu is free from the case, can you unplug the mains lead... install it the reverse way and you never will have a problem.
I have been working on computers for 15 years and when the old pcs had Static sensitive devices, the working on pc's was a lot more stringent as when a motherboard went wrong, you repaired it! now when a motherboard goes wrong, you replace it!
Always remember, if in doubt dont do it!
If you want to get pedantic about static, then the former post is correct: You only really need to be connected via your strap to the PC chassis. This is because the damage is done as a result of potential difference between you and your PC....if you strap yourself to the PC, no PD can develop so no damage can be done. [My professional response is that I do advise having the PC earthed however just to be doubley safe]
In PC factories, the PC is earthed to a solid earth, the assembling person is earthed to said point, and therefore both items are earthed to each other. This is similar to the former poster who says he leaves the mains lead plugged into his 13A socket (albeit switched off..(!!!))
Wrist straps have built-in 1meg resistors so no additional shock risk is present for anyone wearing a strap whether working on live or dead equipment anyhow....
By the way just seen Tony Christie perform Amarillo live. Just like the single....no degredation of voice whatsoever.
In PC factories, the PC is earthed to a solid earth, the assembling person is earthed to said point, and therefore both items are earthed to each other. This is similar to the former poster who says he leaves the mains lead plugged into his 13A socket (albeit switched off..(!!!))
Wrist straps have built-in 1meg resistors so no additional shock risk is present for anyone wearing a strap whether working on live or dead equipment anyhow....
By the way just seen Tony Christie perform Amarillo live. Just like the single....no degredation of voice whatsoever.
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